<!DOCTYPE html>
<html lang="zh" dir="ltr" class="client-nojs">
<head>
<title>this 指针</title>
<meta charset="UTF-8">
<meta name="generator" content="MediaWiki 1.21.2">
<link rel="shortcut icon" href="../../../common/favicon.ico">
<link rel="stylesheet" href="../../../common/ext.css">
<meta name="ResourceLoaderDynamicStyles" content="">
<link rel="stylesheet" href="../../../common/site_modules.css">
<style>a:lang(ar),a:lang(ckb),a:lang(fa),a:lang(kk-arab),a:lang(mzn),a:lang(ps),a:lang(ur){text-decoration:none}#toc{display:none}.editsection{display:none}
/* cache key: mwiki1-mwiki_zh_:resourceloader:filter:minify-css:7:15cea3ec788a65b5187d4018eed543bf */</style>

<script src="../../../common/startup_scripts.js"></script>
<script>if(window.mw){
mw.config.set({"wgCanonicalNamespace":"","wgCanonicalSpecialPageName":false,"wgNamespaceNumber":0,"wgPageName":"cpp/language/this","wgTitle":"cpp/language/this","wgCurRevisionId":72920,"wgArticleId":2758,"wgIsArticle":true,"wgAction":"view","wgUserName":null,"wgUserGroups":["*"],"wgCategories":["Pages with unreviewed CWG DR marker"],"wgBreakFrames":false,"wgPageContentLanguage":"zh","wgSeparatorTransformTable":["",""],"wgDigitTransformTable":["",""],"wgDefaultDateFormat":"zh","wgMonthNames":["","1月","2月","3月","4月","5月","6月","7月","8月","9月","10月","11月","12月"],"wgMonthNamesShort":["","1月","2月","3月","4月","5月","6月","7月","8月","9月","10月","11月","12月"],"wgRelevantPageName":"cpp/language/this","wgUserVariant":"zh","wgRestrictionEdit":[],"wgRestrictionMove":[]});
}</script><script>if(window.mw){
mw.loader.implement("user.options",function(){mw.user.options.set({"ccmeonemails":0,"cols":80,"date":"default","diffonly":0,"disablemail":0,"disablesuggest":0,"editfont":"default","editondblclick":0,"editsection":0,"editsectiononrightclick":0,"enotifminoredits":0,"enotifrevealaddr":0,"enotifusertalkpages":1,"enotifwatchlistpages":0,"extendwatchlist":0,"externaldiff":0,"externaleditor":0,"fancysig":0,"forceeditsummary":0,"gender":"unknown","hideminor":0,"hidepatrolled":0,"imagesize":2,"justify":0,"math":1,"minordefault":0,"newpageshidepatrolled":0,"nocache":0,"noconvertlink":0,"norollbackdiff":0,"numberheadings":0,"previewonfirst":0,"previewontop":1,"quickbar":5,"rcdays":7,"rclimit":50,"rememberpassword":0,"rows":25,"searchlimit":20,"showhiddencats":0,"showjumplinks":1,"shownumberswatching":1,"showtoc":0,"showtoolbar":1,"skin":"cppreference2","stubthreshold":0,"thumbsize":2,"underline":2,"uselivepreview":0,"usenewrc":0,"watchcreations":0,"watchdefault":0,"watchdeletion":0,
"watchlistdays":3,"watchlisthideanons":0,"watchlisthidebots":0,"watchlisthideliu":0,"watchlisthideminor":0,"watchlisthideown":0,"watchlisthidepatrolled":0,"watchmoves":0,"wllimit":250,"variant":"zh","language":"zh","searchNs0":true,"searchNs1":false,"searchNs2":false,"searchNs3":false,"searchNs4":false,"searchNs5":false,"searchNs6":false,"searchNs7":false,"searchNs8":false,"searchNs9":false,"searchNs10":false,"searchNs11":false,"searchNs12":false,"searchNs13":false,"searchNs14":false,"searchNs15":false,"gadget-MathJax":1,"gadget-ColiruCompiler":1});;},{},{});mw.loader.implement("user.tokens",function(){mw.user.tokens.set({"editToken":"+\\","patrolToken":false,"watchToken":false});;},{},{});
/* cache key: mwiki1-mwiki_zh_:resourceloader:filter:minify-js:7:258d7cd6aa9aa67dee25e01fb6a9e505 */
}</script>
<script>if(window.mw){
mw.loader.load(["mediawiki.page.startup","mediawiki.legacy.wikibits","mediawiki.legacy.ajax"]);
}</script>
<style type="text/css">/*<![CDATA[*/
.source-cpp {line-height: normal;}
.source-cpp li, .source-cpp pre {
	line-height: normal; border: 0px none white;
}
/**
 * GeSHi Dynamically Generated Stylesheet
 * --------------------------------------
 * Dynamically generated stylesheet for cpp
 * CSS class: source-cpp, CSS id: 
 * GeSHi (C) 2004 - 2007 Nigel McNie, 2007 - 2008 Benny Baumann
 * (http://qbnz.com/highlighter/ and http://geshi.org/)
 * --------------------------------------
 */
.cpp.source-cpp .de1, .cpp.source-cpp .de2 {font: normal normal 1em/1.2em monospace; margin:0; padding:0; background:none; vertical-align:top;}
.cpp.source-cpp  {font-family:monospace;}
.cpp.source-cpp .imp {font-weight: bold; color: red;}
.cpp.source-cpp li, .cpp.source-cpp .li1 {font-weight: normal; vertical-align:top;}
.cpp.source-cpp .ln {width:1px;text-align:right;margin:0;padding:0 2px;vertical-align:top;}
.cpp.source-cpp .li2 {font-weight: bold; vertical-align:top;}
.cpp.source-cpp .kw1 {color: #0000dd;}
.cpp.source-cpp .kw2 {color: #0000ff;}
.cpp.source-cpp .kw3 {color: #0000dd;}
.cpp.source-cpp .kw4 {color: #0000ff;}
.cpp.source-cpp .co1 {color: #909090;}
.cpp.source-cpp .co2 {color: #339900;}
.cpp.source-cpp .coMULTI {color: #ff0000; font-style: italic;}
.cpp.source-cpp .es0 {color: #008000; font-weight: bold;}
.cpp.source-cpp .es1 {color: #008000; font-weight: bold;}
.cpp.source-cpp .es2 {color: #008000; font-weight: bold;}
.cpp.source-cpp .es3 {color: #008000; font-weight: bold;}
.cpp.source-cpp .es4 {color: #008000; font-weight: bold;}
.cpp.source-cpp .es5 {color: #008000; font-weight: bold;}
.cpp.source-cpp .br0 {color: #008000;}
.cpp.source-cpp .sy0 {color: #008000;}
.cpp.source-cpp .sy1 {color: #000080;}
.cpp.source-cpp .sy2 {color: #000040;}
.cpp.source-cpp .sy3 {color: #000040;}
.cpp.source-cpp .sy4 {color: #008080;}
.cpp.source-cpp .st0 {color: #008000;}
.cpp.source-cpp .nu0 {color: #000080;}
.cpp.source-cpp .nu6 {color: #000080;}
.cpp.source-cpp .nu8 {color: #000080;}
.cpp.source-cpp .nu12 {color: #000080;}
.cpp.source-cpp .nu16 {color:#000080;}
.cpp.source-cpp .nu17 {color:#000080;}
.cpp.source-cpp .nu18 {color:#000080;}
.cpp.source-cpp .nu19 {color:#000080;}
.cpp.source-cpp .ln-xtra, .cpp.source-cpp li.ln-xtra, .cpp.source-cpp div.ln-xtra {background-color: #ffc;}
.cpp.source-cpp span.xtra { display:block; }

/*]]>*/
</style><!--[if lt IE 7]><style type="text/css">body{behavior:url("/mwiki/skins/cppreference2/csshover.min.htc")}</style><![endif]--></head>
<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_language_this skin-cppreference2 action-view cpp-navbar">
        <!-- header -->
        <!-- /header -->
        <!-- content -->
<div id="cpp-content-base">
            <div id="content">
                <a id="top"></a>
                <div id="mw-js-message" style="display:none;"></div>
                                <!-- firstHeading -->
<h1 id="firstHeading" class="firstHeading">this 指针</h1>
                <!-- /firstHeading -->
                <!-- bodyContent -->
                <div id="bodyContent">
                                        <!-- tagline -->
                    <div id="siteSub">来自cppreference.com</div>
                    <!-- /tagline -->
                                        <!-- subtitle -->
                    <div id="contentSub"><span class="subpages">&lt; <a href="../../cpp.html" title="cpp">cpp</a>‎ | <a href="../language.html" title="cpp/language">language</a></span></div>
                    <!-- /subtitle -->
                                                            <!-- bodycontent -->
                    <div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr"><div class="t-navbar" style=""><div class="t-navbar-sep"> </div><div class="t-navbar-head"><a href="../../cpp.html" title="cpp"> C++</a><div class="t-navbar-menu"><div><div><table class="t-nv-begin" cellpadding="0" style="line-height:1.1em">
<tr class="t-nv"><td colspan="5"> <a href="../language.html" title="cpp/language">语言</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../header.html" title="cpp/header">标准库头文件</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../freestanding.html" title="cpp/freestanding"> 自立与有宿主实现</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../named_req.html" title="cpp/named req">具名要求</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../utility.html#.E8.AF.AD.E8.A8.80.E6.94.AF.E6.8C.81" title="cpp/utility">语言支持库</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../concepts.html" title="cpp/concepts">概念库</a> <span class="t-mark-rev t-since-cxx20">(C++20)</span> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../error.html" title="cpp/error">诊断库</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../utility.html" title="cpp/utility">工具库</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../string.html" title="cpp/string">字符串库</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../container.html" title="cpp/container">容器库</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../iterator.html" title="cpp/iterator">迭代器库</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../ranges.html" title="cpp/ranges"> 范围库</a> <span class="t-mark-rev t-since-cxx20">(C++20)</span> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../algorithm.html" title="cpp/algorithm">算法库</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../numeric.html" title="cpp/numeric">数值库</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../locale.html" title="cpp/locale">本地化库</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../io.html" title="cpp/io">输入/输出库</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../filesystem.html" title="cpp/filesystem">文件系统库</a> <span class="t-mark-rev t-since-cxx17">(C++17)</span> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../regex.html" title="cpp/regex">正则表达式库</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../atomic.html" title="cpp/atomic">原子操作库</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../thread.html" title="cpp/thread">线程支持库</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../experimental.html" title="cpp/experimental">技术规范</a> </td></tr>
</table></div><div></div></div></div></div><div class="t-navbar-sep"> </div><div class="t-navbar-head"><a href="../language.html" title="cpp/language">C++ 语言</a></div><div class="t-navbar-sep"> </div><div class="t-navbar-head"><a href="classes.html" title="cpp/language/classes">类</a><div class="t-navbar-menu"><div><div style="display:inline-block">
<div><table class="t-nv-begin" cellpadding="0" style="line-height:1.1em">
<tr class="t-nv-h2"><td colspan="5">概述</td></tr>
<tr class="t-nv"><td colspan="5"> <a href="classes.html" title="cpp/language/classes">综述</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="class.html" title="cpp/language/class"><code>class</code>/<code>struct</code> 类型</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="union.html" title="cpp/language/union"><code>union</code> 类型</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="injected-class-name.html" title="cpp/language/injected-class-name">注入类名</a> </td></tr>
<tr class="t-nv-h2"><td colspan="5">成员</td></tr>
<tr class="t-nv"><td colspan="5"> <a href="data_members.html" title="cpp/language/data members">数据成员</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="static.html" title="cpp/language/static">静态成员</a></td></tr>
<tr class="t-nv"><td colspan="5"> <strong class="selflink"><code>this</code> 指针</strong></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="nested_classes.html" title="cpp/language/nested types">嵌套类</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="member_template.html" title="cpp/language/member template">成员模板</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="bitfield.html" title="cpp/language/bit field">位域</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="using_declaration.html" title="cpp/language/using declaration"><code>using</code> 声明</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="member_functions.html" title="cpp/language/member functions">成员函数</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="access.html" title="cpp/language/access">成员访问指定符</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="initializer_list.html" title="cpp/language/constructor">构造函数与成员初始化器列表</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="data_members.html#.E6.88.90.E5.91.98.E5.88.9D.E5.A7.8B.E5.8C.96" title="cpp/language/data members">默认成员初始化器</a><span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="friend.html" title="cpp/language/friend"><code>friend</code> 说明符</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="explicit.html" title="cpp/language/explicit"><code>explicit</code> 说明符</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="converting_constructor.html" title="cpp/language/converting constructor">转换构造函数</a></td></tr>
<tr class="t-nv-h2"><td colspan="5">特殊成员函数</td></tr>
<tr class="t-nv"><td colspan="5"> <a href="default_constructor.html" title="cpp/language/default constructor">默认构造函数</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="copy_constructor.html" title="cpp/language/copy constructor">复制构造函数</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="move_constructor.html" title="cpp/language/move constructor">移动构造函数</a><span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="copy_assignment.html" title="cpp/language/copy assignment">复制赋值运算符</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="move_assignment.html" title="cpp/language/move assignment">移动赋值运算符</a><span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="destructor.html" title="cpp/language/destructor">析构函数</a></td></tr>
<tr class="t-nv-h2"><td colspan="5">继承</td></tr>
<tr class="t-nv"><td colspan="5"> <a href="derived_class.html" title="cpp/language/derived class">基与派生类</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="ebo.html" title="cpp/language/ebo">空基类优化</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="virtual.html" title="cpp/language/virtual">虚成员函数</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="abstract_class.html" title="cpp/language/abstract class">纯虚函数与抽象类</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="override.html" title="cpp/language/override"><tt>override</tt></a><span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="final.html" title="cpp/language/final"><tt>final</tt></a><span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
</table></div>
</div><div></div></div></div></div><div class="t-navbar-sep"> </div></div>
<h3><span class="mw-headline" id=".E8.AF.AD.E6.B3.95">语法</span></h3>
<table class="t-sdsc-begin">

<tr>
<td colspan="10" class="t-sdsc-sep">
</td></tr>
<tr class="t-sdsc">
<td class="t-sdsc-nopad"> <code><b>this</b></code>
</td>
<td class="t-sdsc-nopad">
</td>
<td class="t-sdsc-nopad">
</td></tr>



<tr>
<td colspan="10" class="t-sdsc-sep">
</td></tr></table>
<p>关键词 <code>this</code> 是一个<a href="value_category.html" title="cpp/language/value category">纯右值</a><a href="expressions.html" title="cpp/language/expressions">表达式</a>，它的值是<a href="overload_resolution.html" title="cpp/language/overload resolution">隐式对象形参</a>（在其上调用非静态成员函数的对象）的地址。它能出现于下列语境：
</p>
<div class="t-li1"><span class="t-li">1)</span> 在任意非静态<a href="member_functions.html" title="cpp/language/member functions">成员函数</a>体内，包括<a href="initializer_list.html" title="cpp/language/initializer list" class="mw-redirect">成员初始化器列表</a></div>
<div class="t-li1"><span class="t-li">2)</span> 在非静态成员函数的<a href="function.html" title="cpp/language/function">声明</a>中，（可能存在的）cv 限定符序列之后的任何位置，包括 <table class="t-rev-begin">
<tr class="t-rev t-until-cxx17"><td>
<ul><li> <a href="except_spec.html" title="cpp/language/except spec">动态异常说明</a>、
</li></ul>
</td>
<td><span class="t-mark-rev t-until-cxx17">(C++17 前)</span></td></tr>
</table>
 <table class="t-rev-begin">
<tr class="t-rev t-since-cxx11"><td>
<ul><li> <a href="noexcept_spec.html" title="cpp/language/noexcept spec">noexcept 说明</a>以及
</li><li> 尾随返回类型
</li></ul>
</td>
<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td></tr>
</table></div>
 <table class="t-rev-begin">
<tr class="t-rev t-since-cxx11"><td>
<div class="t-li1"><span class="t-li">3)</span> 在<a href="data_members.html#.E6.88.90.E5.91.98.E5.88.9D.E5.A7.8B.E5.8C.96" title="cpp/language/data members">默认成员初始化器</a>中
</div></td>
<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td></tr>
</table>
<p>在类 <code>X</code> 的成员函数中，<code>this</code> 的类型是 <code>X*</code>（指向 X 的指针）。如果成员函数有 <a href="member_functions.html" title="cpp/language/member functions">cv 限定</a>，那么 <code>this</code> 的类型是 <code>cv X*</code>（指向有相同 cv 限定的 X 的指针）。因为构造函数与析构函数不能有 cv 限定，所以它们中 <code>this</code> 的类型始终是 <code>X*</code>，即使在构造或销毁 const 对象时也是如此。
</p><p>当在任何允许 <code>this</code> 关键词的语境（非静态成员函数体、成员初始化器列表、默认成员初始化器）中使用非静态数据成员时，它的名字前会自动添加隐含的 <code><b>this-&gt;</b></code>，产生一个成员访问表达式（如果该成员是虚成员函数，那么产生虚函数调用）。
</p><p>在类模板中，<code>this</code> 是一个<a href="dependent_name.html" title="cpp/language/dependent name">待决表达式</a>，而且显式的 <code>this-&gt;</code> 可以用于强行使另一表达式变为待决的。
</p>
<div dir="ltr" class="mw-geshi" style="text-align: left;"><div class="cpp source-cpp"><pre class="de1"><span class="kw1">template</span><span class="sy1">&lt;</span><span class="kw1">typename</span> T<span class="sy1">&gt;</span>
<span class="kw1">struct</span> B
<span class="br0">{</span>
    <span class="kw4">int</span> var<span class="sy4">;</span>
<span class="br0">}</span><span class="sy4">;</span>
 
<span class="kw1">template</span><span class="sy1">&lt;</span><span class="kw1">typename</span> T<span class="sy1">&gt;</span>
<span class="kw1">struct</span> D <span class="sy4">:</span> B<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span>
<span class="br0">{</span>
    D<span class="br0">(</span><span class="br0">)</span>
    <span class="br0">{</span>
        <span class="co1">// var = 1;    // 错误： 'var' 未在此作用域中声明</span>
        this<span class="sy2">-</span><span class="sy1">&gt;</span>var <span class="sy1">=</span> <span class="nu0">1</span><span class="sy4">;</span> <span class="co1">// OK</span>
    <span class="br0">}</span>
<span class="br0">}</span><span class="sy4">;</span></pre></div></div>
<p>在对象的<a href="initializer_list.html" title="cpp/language/constructor">构造期间</a>，如果通过并非直接或间接从构造函数的 <code>this</code> 指针获得的泛左值访问对象或其任何子对象的值，那么如此获得的对象或子对象的值是未指明的。换言之，构造函数中 this 指针不能被别名化：
</p>
<div dir="ltr" class="mw-geshi" style="text-align: left;"><div class="cpp source-cpp"><pre class="de1"><span class="kw4">extern</span> <span class="kw1">struct</span> D d<span class="sy4">;</span>
<span class="kw1">struct</span> D
<span class="br0">{</span>
    D<span class="br0">(</span><span class="kw4">int</span> a<span class="br0">)</span> <span class="sy4">:</span> a<span class="br0">(</span>a<span class="br0">)</span>, b<span class="br0">(</span>d.<span class="me1">a</span><span class="br0">)</span> <span class="br0">{</span><span class="br0">}</span> <span class="co1">// b(a) 或 b(this-&gt;a) 是正确的</span>
    <span class="kw4">int</span> a, b<span class="sy4">;</span>
<span class="br0">}</span><span class="sy4">;</span>
D d <span class="sy1">=</span> D<span class="br0">(</span><span class="nu0">1</span><span class="br0">)</span><span class="sy4">;</span>   <span class="co1">// 因为 b(d.a) 未通过 this 访问，所以 d.b 现在是未指明的</span></pre></div></div>
<p>如果程序能保证对象由 <span class="t-c"><span class="mw-geshi cpp source-cpp">new</span></span> 分配，那么可以执行 <span class="t-c"><span class="mw-geshi cpp source-cpp">delete this<span class="sy4">;</span></span></span>，然而这会令指向被解分配对象的所有指针失效，包括 <code>this</code> 指针自身：在 <span class="t-c"><span class="mw-geshi cpp source-cpp">delete this<span class="sy4">;</span></span></span> 返回后，这种成员函数不能引用类的成员（因为这牵涉到 <code>this</code> 的隐式解引用），且不可再调用其他成员函数。
</p>
 <table class="t-rev-begin">
<tr class="t-rev t-since-cxx11"><td>
<p>例如，这被用于 <span class="t-lc"><a href="../memory/shared_ptr.html" title="cpp/memory/shared ptr">std::shared_ptr</a></span> 的控制块的负责减少引用数的成员函数中，在最后一个到被管理对象的引用离开作用域时。
</p>
</td>
<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td></tr>
</table>
<div dir="ltr" class="mw-geshi" style="text-align: left;"><div class="cpp source-cpp"><pre class="de1"><span class="kw1">class</span> ref
<span class="br0">{</span>
    <span class="co1">// ...</span>
    <span class="kw4">void</span> incRef<span class="br0">(</span><span class="br0">)</span> <span class="br0">{</span> <span class="sy2">++</span>mnRef<span class="sy4">;</span> <span class="br0">}</span>
    <span class="kw4">void</span> decRef<span class="br0">(</span><span class="br0">)</span> <span class="br0">{</span> <span class="kw1">if</span> <span class="br0">(</span><span class="sy2">--</span>mnRef <span class="sy1">==</span> <span class="nu0">0</span><span class="br0">)</span> delete this<span class="sy4">;</span> <span class="br0">}</span>
<span class="br0">}</span><span class="sy4">;</span></pre></div></div>
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
<div dir="ltr" class="mw-geshi" style="text-align: left;"><div class="cpp source-cpp"><pre class="de1"><span class="kw1">class</span> T
<span class="br0">{</span>
    <span class="kw4">int</span> x<span class="sy4">;</span>
 
    <span class="kw4">void</span> foo<span class="br0">(</span><span class="br0">)</span>
    <span class="br0">{</span>
        x <span class="sy1">=</span> <span class="nu0">6</span><span class="sy4">;</span>       <span class="co1">// 等同于 this-&gt;x = 6;</span>
        this<span class="sy2">-</span><span class="sy1">&gt;</span>x <span class="sy1">=</span> <span class="nu0">5</span><span class="sy4">;</span> <span class="co1">// 显式使用 this-&gt;</span>
    <span class="br0">}</span>
 
    <span class="kw4">void</span> foo<span class="br0">(</span><span class="br0">)</span> <span class="kw4">const</span>
    <span class="br0">{</span>
<span class="co1">//        x = 7; // 错误：*this 是常量</span>
    <span class="br0">}</span>
 
    <span class="kw4">void</span> foo<span class="br0">(</span><span class="kw4">int</span> x<span class="br0">)</span> <span class="co1">// 形参 x 遮蔽拥有相同名字的成员</span>
    <span class="br0">{</span>
        this<span class="sy2">-</span><span class="sy1">&gt;</span>x <span class="sy1">=</span> x<span class="sy4">;</span> <span class="co1">// 无限定的 x 代表形参</span>
                     <span class="co1">// 需要用‘this-&gt;’消歧义</span>
    <span class="br0">}</span>
 
    <span class="kw4">int</span> y<span class="sy4">;</span>
    T<span class="br0">(</span><span class="kw4">int</span> x<span class="br0">)</span> <span class="sy4">:</span> x<span class="br0">(</span>x<span class="br0">)</span>, <span class="co1">// 用形参 x 初始化成员 x</span>
               y<span class="br0">(</span>this<span class="sy2">-</span><span class="sy1">&gt;</span>x<span class="br0">)</span> <span class="co1">// 用成员 x 初始化成员 y</span>
    <span class="br0">{</span><span class="br0">}</span>
 
    T<span class="sy3">&amp;</span> operator<span class="sy1">=</span> <span class="br0">(</span> <span class="kw4">const</span> T<span class="sy3">&amp;</span> b <span class="br0">)</span>
    <span class="br0">{</span>
        x <span class="sy1">=</span> b.<span class="me1">x</span><span class="sy4">;</span>
        <span class="kw1">return</span> <span class="sy2">*</span>this<span class="sy4">;</span> <span class="co1">// 许多重载运算符都返回 *this</span>
    <span class="br0">}</span>
<span class="br0">}</span><span class="sy4">;</span>
 
<span class="kw1">class</span> Outer <span class="br0">{</span>
    <span class="kw4">int</span> a<span class="br0">[</span>sizeof<span class="br0">(</span><span class="sy2">*</span>this<span class="br0">)</span><span class="br0">]</span><span class="sy4">;</span> <span class="co1">// 错误：不在成员函数中</span>
    <span class="kw4">unsigned</span> <span class="kw4">int</span> sz <span class="sy1">=</span> sizeof<span class="br0">(</span><span class="sy2">*</span>this<span class="br0">)</span><span class="sy4">;</span> <span class="co1">// OK：在默认成员初始化器中</span>
    <span class="kw4">void</span> f<span class="br0">(</span><span class="br0">)</span> <span class="br0">{</span>
        <span class="kw4">int</span> b<span class="br0">[</span>sizeof<span class="br0">(</span><span class="sy2">*</span>this<span class="br0">)</span><span class="br0">]</span><span class="sy4">;</span> <span class="co1">// OK</span>
        <span class="kw1">struct</span> Inner <span class="br0">{</span>
            <span class="kw4">int</span> c<span class="br0">[</span>sizeof<span class="br0">(</span><span class="sy2">*</span>this<span class="br0">)</span><span class="br0">]</span><span class="sy4">;</span> <span class="co1">// 错误：不在 Inner 的成员函数中</span>
        <span class="br0">}</span><span class="sy4">;</span>
    <span class="br0">}</span>
<span class="br0">}</span></pre></div></div>

<!-- 
NewPP limit report
Preprocessor visited node count: 1433/1000000
Preprocessor generated node count: 4230/1000000
Post‐expand include size: 44289/2097152 bytes
Template argument size: 6945/2097152 bytes
Highest expansion depth: 14/40
Expensive parser function count: 0/100
-->

<!-- Saved in parser cache with key mwiki1-mwiki_zh_:pcache:idhash:2758-0!*!0!!*!*!zh!* and timestamp 20211107124338 -->
</div>                    <!-- /bodycontent -->
                                        <!-- printfooter -->
                    <div class="printfooter">
                    来自“<a href="https://zh.cppreference.com/mwiki/index.php?title=cpp/language/this&amp;oldid=72920">https://zh.cppreference.com/mwiki/index.php?title=cpp/language/this&amp;oldid=72920</a>”                    </div>
                    <!-- /printfooter -->
                                                            <!-- catlinks -->
                    <!-- /catlinks -->
                                                            <div class="visualClear"></div>
                    <!-- debughtml -->
                                        <!-- /debughtml -->
                </div>
                <!-- /bodyContent -->
            </div>
        </div>
        <!-- /content -->
        <!-- footer -->
        <div id="cpp-footer-base" class="noprint">
            <div id="footer">
                        <div id="cpp-navigation">
            <h5>导航</h5>
            <ul><li><a href="https://zh.cppreference.com/w/cpp/language/this">Online version</a></li><li>Offline version retrieved 2022-01-01 00:37.</li></ul></div>
                        <ul id="footer-info">
                                    <li id="footer-info-lastmod"> 本页面最后修改于2021年11月7日 (星期日) 03:19。</li>
                                    <li id="footer-info-viewcount">此页面已被浏览过8,879次。</li>
                            </ul>
                    </div>
        </div>
        <!-- /footer -->
        <script>if(window.mw){
mw.loader.state({"site":"loading","user":"missing","user.groups":"ready"});
}</script>
<script src="../../../common/skin_scripts.js"></script>
<script>if(window.mw){
mw.loader.load(["mediawiki.action.view.postEdit","mediawiki.user","mediawiki.page.ready","mediawiki.searchSuggest","mediawiki.hidpi","ext.gadget.MathJax","ext.gadget.ColiruCompiler"], null, true);
}</script>
<script src="../../../common/site_scripts.js"></script>
<script type="text/javascript">
var _gaq = _gaq || [];
_gaq.push(['_setAccount', 'UA-2828341-1']);
_gaq.push(['_setDomainName', 'cppreference.com']);
_gaq.push(['_trackPageview']);
</script><!-- Served in 0.070 secs. -->
	</body>
<!-- Cached 20211107193227 -->
</html>